Project Summary/Abstract The focus of this renewal application is to leverage the platform from which we successfully launched the Social Media and Risk Reduction Training (SMART) study, a randomized trial using mobile health (mHealth) strategies to improve caregiver adherence to American Academy of Pediatrics (AAP)-recommended infant care practices related to safe sleep, and to enhance the reach by adding a culturally-sensitive prenatal education component and specifically targeting low-income populations who are most at risk for sleep-related infant deaths. SMART was proposed to design, implement, and assess the effectiveness of interventions to prevent Sudden Infant Death Syndrome (SIDS) and unintentional injury-related infant deaths associated with the sleep environment. These deaths, which we will refer to as sleep-related deaths, remain the leading cause of postneonatal death in the United States, with ~3500 deaths each year. Many of these deaths are preventa- ble with improved adherence to AAP safe infant sleep guidelines. A key finding from SMART was that nursery-based education alone was not effective, but a technology- based mHealth messaging intervention was ? mothers receiving safe sleep mHealth messages had ~10 per- centage point higher rates of following safe sleep practices. Our proposed SMARTER (Social Media and Risk Reduction Teaching- Enhanced Reach) study is the natural next step towards the full translation into practice of SMART. The SMARTER study plans a 4-arm pragmatic RCT in which 2500 pregnant mothers recruited at Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) programs in 2 states (MA and VA) are randomly assigned to a combination of safe sleep and breastfeeding mHealth interventions prenatally and postnatally: 1) Safe Sleep Prenatal and Breastfeeding Postnatal; 2) Breastfeeding Prenatal and Safe Sleep Postnatal; 3) Safe Sleep Prenatal and Postnatal; and 4) Breastfeeding Prenatal and Postnatal. This combination of study conditions will allow us to evaluate message content, timing, and dose of uptake and maintenance of safe sleep and breastfeeding practices through 6 months after birth. The primary aim is to as- sess the effectiveness of the mHealth prenatal and postnatal interventions aimed at promoting safe sleep prac- tices and breastfeeding. The secondary aim is to assess potential mediating factors that may explain the inter- vention effects on infant care practices and inform areas for improving future intervention approaches.